Abstract Outcomes in patients with relapsed diffuse large B-cell lymphoma (DLBCL) who undergo autologous stem cell transplant (auto-SCT) are poor. Blinatumomab is a CD3/CD19 bispecific T-cell engager that directs cytotoxic T cells to CD19+ cells. Here, we performed a pilot study of blinatumomab consolidation after auto-SCT for 14 patients with DLBCL or transformed follicular lymphoma. All patients underwent standard-of-care auto-SCT with carmustine, etoposide, cytarabine, and melphalan (BEAM) conditioning followed by 1 cycle (4 weeks continuous infusion) of blinatumomab consolidation starting at day 42 after auto-SCT. All 14 patients treated on study completed BEAM auto-SCT and 1 cycle of posttransplant blinatumomab. Five patients developed grade 1 cytokine release syndrome (CRS), with no grade 2 or higher CRS. Immune effector cell–associated neurotoxicity syndrome was not observed. Patients were followed up for 3 years after auto-SCT, with median follow-up of 37 (range, 12-65) months. One-hundred days after auto-SCT (1 month after blinatumomab consolidation), 12 patients (86%) had achieved complete remission. At 1 year after auto-SCT, 7 patients (50%) remained in CR, and 1 patient had died of progressive disease. Patients who relapsed had a lower CD8:CD4 T-cell ratio before starting blinatumomab than patients who remained in remission. This pilot study demonstrates blinatumomab consolidation after auto-SCT is safe and well tolerated. Strategies to increase the CD8:CD4 ratio and use additional cycles of consolidation in a larger randomized trial are needed to confirm the efficacy of consolidation with blinatumomab after auto-SCT. This trial was registered at www.clinicaltrials.gov as #NCT03072771.